Drill steel rod



July 15, c P, HAMMOND r DRILL STEEL ROD Filed July 25, 1945 2 Sheets-Sheet 1 \NVENTORS= C. P. HAMMOND A M.CAMERON.

July 15, 1947. A c. P. HAMMOND ETAL 2,424,092

DRILL STEEL ROD Filed July 25, 1945 2 Sheets-Sheet 2 INVENTORS:

C. P. HAMMOND; A. M. CAMERON.

Patented July 15, 1947 DRILL STEEL ROD Charles Percy Hammond and Allister McKenzie Cameron, Welland, Ontario, Canada, assignors to Atlas Steels Limited, Welland, Ontario, Canada, a company of Canada Application July 25, 1945, Serial No. 606,900

1 Claim.

This invention relates to drill steels used for rock drilling, etc., and pertains in particular to hollow drill steels such as used in the mining fields.

Drill steels of this kind are subjected in use to a combination of fiexural, vibratory and shock stresses which result in the ultimate fatigue of the steel. As a result, therefore, breakages occur after a period of use and in many cases before a reasonable period of use has been attained. In some cases it is possible to use broken lengths of the steel providing that they break towards the I end of a section, thus leaving a length of rod which can be employed usefully.

Drill steel rods of octagonal and hexagonal cross-section are most widely used, the octagonal shaped rod being commonly known as quarter octagon because of the fact that it is of generally square character in cross-section with the corners substituted by flat narrow portions disposed at an angle to the plane of the four main sides of the rod, and these shapes are formed by rolling after the steel billets have been reduced by successive rollings to a, predetermined size. However, due to the fact that on diagonally opposite corners of the hexagonal and octagonal drill rod sections, it is impossible to cause the rolls to engage the surface of the corner. These corners when produced are pitted and roughened and contrast somewhat with the opposite corners. As a result, therefore, fractures occur which can be traced primarily to this cause since a roughened or pitted surface will lead to strain and fracture. corners that are formed as a result of the corner formations of hexagonal and quater octagon drill sections, such corners are liable to nicking and scoring in use and accordingly this leads very often to fracture when the section is under strain of use.

These disadvantages are largely avoided by the present invention.

It is an object Of the present invention to provide a new drill rod section which will be subject to longer life and lessened hazard of fracture.

A further object of the invention is to provide a drill steel section which in terms of substantially similar or slightly less cross-sectional area as compared to quarter octagon or hexagonal drill sections will provide a greater surface area having the effect of reducing the average unit stress.

A further object of the invention is to provide a drill steel section of this kind which will pro- Moreover, due to the relatively sharp vide an actually greater perimeter formed by an alternating concave-convex contour and smooth curved surface to increase resistance to fatigue and shock effect by a wider dissipation of stresses at the surface of the section or rod.

A further object of the invention i to provide a drill section of generally hexagonal or octagonal cross-section eliminating all sharp or near sharp corners.

A further object of the invention is to provide a drill section of this kind in which the section will be basically stiffer in terms of deflection unler given load in comparison to a drill section of hexagonal or quarter octagon section of equal cross-sectional area.

A further object of the invention is to provide a drill section of this kind wherein the corner areas of the drill section will be less roughened or pitted than in the case of conventional hexagonal or quarter octagon drill sections.

A still further object of the invention is to provide a drill steel section of this kind which is less sensitive to unavoidable use in handling and operation such a to reduce nicks, scores and wear which ordinarily result in conventional drill steel sections.

A still further object of the invention is to provide a drill steel section which, due to the provision of an alternating concave and convex surface, will provide for a greater shank life by permitting the grit and particles of steel to work out of the drill chuck during drilling operations.

A still further object of the invention is to provide a drill steel section which, due to its contour, will cause said section to be more completely under compression during the rolling operation and which will largely eliminate roughened surface areas which occur in conventional drill steel.

With these and other objects in view, the invention generally comprises a drill steel rod or bar formed with an alternating concave and convex contour, which may be produced in a hexagonal or octagonal form and in which the corners of the section are rounded to provide a continuous substantially smooth surface throughout the perimeter of the section and an increase in diameter along the diagonal lines extending between the corners and through the center of the section, and producing'in result a drill steel section of greater durability as will be clearly understood by reference to the following detailed specification taken in conjunction with the accompanying drawings.

In the drawings:

Fig. l is a cross-sectional view of a conventional quarter octagon drill steel as commonly used.

Fig. 2 is a cross-section of a drill steel rod according to the present invention of a shape generally corresponding to quarter octagon shape of the prior art.

3 is a transverse section taken thr h a quarter octagon drill steel of the prior art showing it located in the chuck of a drill.

Fig. 4 is a cross-sectional view similar to Fig. 3 but taken through a drill steel section of the present invention to show it inserted in a drill chuck of corresponding size to that illustrated in'Fig. 2.

Fig. 5 is a fragmentaryperspective-view of a drill steel section of the kind shown inFig. 2.

Fig. 6 is a fragmentary perspective view of a drill steel section according to the present invention substantially corresponding to the hexagonal type of drill steel section of theprior art.

Figure 7 shows a quarter octagon drill steel section of the prior artpassing through the forming rolls, the latter being illustrated fragmen- .tarily; and

. Figure 8 is a similar view to Figure '7 showing a fragmentary schematic viewof a drill steel section of the present invention-passing. through the forming rolls, the latter being shown fragmentarily.

Referring to the drawings, A indicates a drill sectionof the prior art commonlyknown as the quarteroctagon sectionandB indicates a, drill section .accordingto the present invention which may be generally termed a clover leaf section byreason of its similarityto a four leaf clover if the corner sections were brought in along thediagonals towards the center. As indicated in .FigslandZ, these sectionshave a generally rectilinear character and, as will be noted by the arrow linesA in each case their overall crosssectionaldimensions are the same. Similarly, by reference to .Figs. '3 and 4, it will be noted that bothsections will 'fitinto the socket of the drill chuck C, even thoughthe. dimensions of the clover leaf section, of the presentinvention, when measured along the diagonals ofa cross-sectional con-,

tour thereof, are of greater length than the diagonalsof the quarter octagon section as referred to hereinafter. This .is due'to thefact-that some clearance is'permitted in the drill chuck, particularly atthecornersfor insertionof the conventional drill rod section. This is equally true in the case of the hexagonal-drill steel section.

The approximate appearance of the drill rod sections according to the present .invention is illustrated-in Figs. 5 and 6 and it will be understood that-in describing the comparative merits of the-quarter octagon with the new clover leaf section of the present invention, that corresponding remarks apply generally'to the hexagonal drillrod section according to the present inventionin-comparison to that'of the prior art.

Referring particularly to'Fig. 2, it will be noted that theclover leaf drillsteelsection according eter of the section and avoids any sharp or nearly sharp corners particularly subject to nicking and scoring during handling and in operation. Accordingly one contributing cause of fracture is largely eliminated. Of even more importance, however, is the reduction to the minimum of pitted or roughened surfaces-on opposed corners of the .drill rod section which are a contributing cause to fracture and failure of drill rod section. This is aptly illustrated by reference to Figs. 7 and. 8.

The drill rod section according to the present invention will permit a greater area of contact between'the forming rolls and the surfaces of the drill rod section which places a larger portion of the section under compression during the final rolling operations and largely eliminates pitted or rough areas at the surface metal on opposed corners where in normal practice it is impossible to obtain roll contact.

Referring to Fig. '7,-the.quarter octagon section A ofthe .prior art is passing between the form ing rolls l3 and Mformed with conical areas IE, to give the flat side contour to the section, and the cylindrical portions 16 which give the flat corner contour on two opposed corners of the section. The remaining two .opposed corners generally indicated-by the numeralll areformed withoutrroll contact as is clearly illustratedand in result, the metal'here is not under complete compression and roughsurface areas along these corners are formedthroughout .their lengths.

In contra-distinctionto this, it will'be noted particularly by reference to Fig. 8'that thesection B according 'to'the "present'invention permits a roll contactgby theflute'd surfaces It: of the rolls it and M substantially throughout its'entire area except for'a very-minor strip indicated. by the numeral 18. Thus, substantially all the section is under compression during the final rolling operations" and the opposed roughened surfacesas created by theprior art above referred to are largely eliminated. It will be apparent, therefore, from this that a contributing cause to fracture and fatigue is largely eliminated. Accordingly, therefore, the drill rod section provides an improvement over that ofthe prior art in'this important consideration.

In additionyhowever, further'advantages stem from the improved contour. Onthe one hand it is clear that the alternate concave and convex contourprovi'cles an increased perimeter which provides agreater surface area having the effect of reducing the average unit stress and it increases resistance to fatigue and shock brought about by a wider distributionof stresse at the surface of the section.

The outside dimensions of this section substantially correspond with the overall'outside dimensions of thequarter octagon section illustrated in Fig. 1, yet it will be noted that by pro viding the rounded corners Ill-formed from equal radii that the diagonals of the cross-section of this rod indicatedby the dotted lines Q-are longer than the corresponding diagonals of the quarter octagon section-of -the' prior art and as'is clearly indicated when'locating; in Fig.2 by way of dotted increasing the operational strength and stiffness of the section, of importance particularly during :operation.

Finally, it should be noted that at least three further advantages are attained. In terms of deflection of the drill rod section of the present invention under a given load, the sections produced according to the present invention are basically stiffer than those of the prior art, having a corresponding cross-sectional area. The formation of the bore of hollow drill steel section is maintained more symmetrically than in the case of the prior art, while the grooves in the exterior surfaces of the drill rod section form passages between the head of the drill rod and the surrounding socket of the drill chuck which receives it, thereby permitting particles to dislodge which normally tend to accumulate in the chuck and having an abrading action on the drill rod.

The drill rod section of the present invention may be produced with equal facility to that of the prior art, while achieving the advantages outlined.

What we claim as our invention is:

A drill steel rod having at least four sides of equal width disposed at an angle to one another and having an undulating perimeter of a series of concave convex curves of equal radius, said section having a dimension measured along the diagonals extending transversely of the rod between opposeo. corners thereof greater than standard rods of equal side width and angular relation which have substantially fiat surfaced corners, said greater dimension being equal to twice the difierence between a chord theoretically drawn from the terminal ends of said rounded corners and the periphery of the curve of said rounded corner at its point of intersection with said diagonal.

CHARLES PERCY HAMMOND.

ALLISTER MCKENZIE CAMERON.

Number Name Date 228,485 Sweet June 8, 1880 2,297,983 Rea Oct. 6, 1942 237,013 Hammond Jan. 25, 1881 

